The 19-year-old world number nine slipped awkwardly while facing Karolina Pliskova on Wednesday, forcing her to retire.
After scans on her left knee, she also pulled out of her doubles quarter-final alongside Serena Williams, the 23-time Grand Slam champion who returned to action this week after a near four-year absence from the sport.
In an Instagram post on Friday, Mboko said she had injured the medial collateral ligament.
Mboko is the third player to withdraw from the Wimbledon main draw since the initial entry list was released, following American Hailey Baptiste and Britain's Sonay Kartal.